Bille wrote:I Really notice that difference whenever i go from Mohaveto the coast in San Diego !

A 25 in the Dry Mohave desert, isn't anywhere Near as strongas that coastal air with the same wind strength. I remember Mohavebeing about 640ft above sea level, so it isn't really an altitude thing.

Bille

640 feet means about 1027mbar so it's about 1% less powerful than sea level wind purely from altitude. The dry air is about 0.05% more powerful than the moist coastal air. With a 20F difference in temperature that's about 1.5% less powerful warm air.

We can feel the dry air very easily so we like to think it affects the kite but it's everything else that's more important.

Like someone else said currents play a large role in power or perceived power. Strong currents can make or break a location. Here in the Houston area Galveston East beach is the main surf spot the problem with it is the strong current that is created from the jetty and shipping channel. Current will normally be with wind so as a personal rule I won't even attempt to kite there unless the forecast is over 20kts.

All so we get lots of pressure bubbles that pushes the wind up higher than our kites. This is because the island really is just a sand bar and until the bay gets hot the wind is really light on the beach. Usually 10kts lighter.

One last thing I will bring up is changing wind directions. Not only will the wind lull and gust it can shift direction. If it is real shifty and changing its angle a lot you could find your self going down wind even though you feel powered. This is really hard to notice and get in sync with. Just the other day I was out and about to pack up when I figured out that it was just shifting. Changed up my tacks with the wind and found myself shooting upwind even though the wind was light and I only really had enough to power to stay upwind with the tide going out.

If you are interested how much, then you should calculate your rho (lbs/cuf or kg/kuM) and multiply it with your kite size. Playing with some numbers shows you exactly how your kite (and its pull) is affected by temp, altitude and dew point.

oh no. The difference you feel is quite real. The problem is that we can feel moisture in the air very easily but we find it very difficult to tell when we are up or down 800 feet in altitude. So we think it's the dry air when it really is the altitude. Or maybe it will be a dry day and the wind gradient is very even, so it's 15mph on the ground and 15mph 20 meters up in the air, but on a moist day the wind gradient might be 15mph on the ground and 25mph 20 meters up in the air. So we think it's the dry air but it's really the wind gradient / altitude / temperature / current etc.